The present invention relates to a gear wheel construction.
More specifically, the present invention relates to a gear wheel construction which can be used in a precision conveyor device including an apron driven by a timing belt.
More specifically, the gear wheel construction according to the invention can be used, in particular, in a conveyor device in which the timing belt slides on a frame, according to at least a top flat path, driven by driving rollers, and being entrained about two end pulleys, at the end portions of its driving path.
At an intermediate region of the top flat driving path, the gear wheel, or toothed pulley, according to the invention, is arranged at a bottom between a pair of flat pulleys which, by cooperating with the subject gear wheel, cause the timing belt to follow a downward directed loop.
The gear wheel is driven by a driving means including, depending on requirements, a step by step motor, a D.C. motor, a brushless motor, the driving means being coupled to the timing belt through a geared unit.
As is known, the apron or conveyor belt devices used in precision processing operations, such as to convey workpiece to a machining tool, must be able of locating the workpiece in a very accurate manner, with respect to the machining tool.
A problem affecting the above disclosed system is that of the wear of the teeth of the gear wheel, with a consequent backlash between the gear wheel and timing belt, which negatively affect the movement precision of the timing belt and apron.
Accordingly, the aim of the present invention is to provide an improved gear wheel construction, which is suitable to overcome the above disclosed drawback.
Within the scope of the above mentioned aim, a main object of the present invention is to provide such a gear wheel which is very simple construction-wise and very reliable in operation.
Another object of the present invention is to provide such a gear wheel construction allowing to recover the backlash due to the wear of the gear wheel teeth, and this by a simple and quick adjusting operation.
According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by a gear wheel construction, characterized in that said gear wheel construction comprises a first gear wheel portion, including first half-teeth, which can be coupled to a second gear wheel portion, including second half-teeth, by adjustable coupling means, thereby said first and second half-teeth form by pairs teeth of said gear wheel, said second gear wheel portion being suitable to turn about said first gear wheel portion, about a rotary axis of said gear wheel, and being locked by said coupling means so as to change the distance of the first and second half teeth in each said pair.